Historically, vibration data analysis in evaluating machinery health is a daunting task. First, only relevant sections of the vibration data require analysis. It may be desirable in some limited cases to analyze steady-state vibration data in order to confirm a minimal level of vibration. However, the relevant sections generally are the transient vibration data sections. Unfortunately, the volume of transient vibration data available for analysis may be unmanageable. For example. one transient analysis system can collect 32 channels of vibration data 5,120 times per second for over 48 hours. An effective analysis of data collected from such a system may necessitate analysis of a single, continuous time waveform containing over 800 million data points.
In order for such a data waveform to be analyzed sufficiently, it must be broken into smaller components or regions. Several different processing methods for sections of vibration data may be used in order to provide diagnostic benefits beyond viewing conventional waveforms and trend data (spectral-based parameter data plotted against time). Also, the different processing methods provide several display opportunities not available with plotted waveforms and trends. The processing and display methods available for vibration analysis include cascade/waterfall plots, average shaft centerline plots and Bode/Nyquist plots.
In order to effectively use the vibration analysis plotting tools discussed above, a user must be able to provide a data context for these alternative displays—that is, to identify the portion of the data to be processed. Additionally, parameters used to construct the plots must also be specified. For these reasons, a method and graphical tool to help users identify the portion of the transient data requiring analysis is needed. Also, construction parameters associated with the graphical tool are needed to help determine how the portion of transient data is sampled in order to populate any derived analysis plots including cascade/waterfall plots, average shaft centerline plots and Bode/Nyquist plots.
A method and apparatus for identifying a region of interest of transient vibration data requiring analysis solves the aforementioned and other problems. In one method for processing and displaying data, transient data is provided and a region of interest leading edge and trailing edge are determined, which together define the portion of transient data requiring analysis. A construction mode is specified corresponding to a derived graphical display of the transient data, and a construction parameter is also specified corresponding to the specified construction mode. The transient data is processed to produce at least one derived plot. The construction mode may be selected from; delta time construction mode, delta rpm construction mode, and fixed number construction mode. The derived plot may be selected from; cascade plots, average shaft centerline plots, and Bode/Nyquist plots.
In one embodiment, a graphical tool is provided for identifying a region of interest representing transient data chosen by a user. The graphical tool also derives and displays an analytical plot from the region of interest. The transient data is collected by a vibration sensing instrument and represents the vibration of a machine, and the transient data is communicated to the graphical tool by the vibration sensing instrument. The graphical tool may include a hardware module and a software module. The hardware module has a processor, a memory, a display, and a communicator. The memory is connected to the processor and stores the software module. The display is also connected to the processor and displays the transient data, the region of interest, and the analytical plots. The communicator is connected to the processor and communicates with the vibration sensing instrument. The software module has a plotting module and a plotcontrol module having a tools module containing tools used by the plotting module.